As part of continuing efforts to increase the functionality of integrated circuits (ICs) such as central processing units (CPUs), there has been a continuing need to provide ever more electrical contacts (commonly referred to as “pins”) on the packages in which ICs are typically encapsulated to enable ever greater interactions between such ICs and other devices. However, increasing the number of electrical connections for a given IC presents the challenge of finding a way to accommodate having an increasing number of contacts mounted on an IC package in a way that will still afford a practical way to attach the IC package (and thereby, attach the IC within) to a circuitboard so that electrical connections with other devices are created.
In answer to this increasing need to provide more electrical contacts for use by an IC, various forms of through-hole pins, surface mount contacts, solder leaf contacts, solder balls, etc. have been devised over time. Where the IC is meant to be permanently attached to a circuitboard, it is possible to devise a layout of electrical contacts on at least one surface of the IC package that will permit those contacts to be soldered to a surface of a circuitboard.
However, there are other situations where the IC must be removably attached to a circuitboard such that an unskilled user of a product in which the circuitboard is installed must be able to attach or detach the IC from the circuitboard without the benefit of a host of specialized tools. In such situations, it is seldom deemed acceptable or desirable to require such a user to solder or desolder an IC encapsulated within a package having a very large number of contacts, and so the use of a socket by which the IC may be removably attached to a circuitboard must be provided for.
Sockets have been devised to support for removably attaching an IC with a PGA package to a circuitboard. However, the use of pins in by a PGA package of an IC requires that the socket be designed to “grab”, the pins with opposing forces sideways along the lengths of the pins to make electrical connections. This requires mechanisms within the socket that limits the possible density of pins and thereby limits the overall practical number of pins on a given package that may be supported. It would be desirable to provide a socket that did not use pins, and therefore, did not require such mechanisms within a socket to use sideways forces.
Sockets could be provided that would rely on contacts of the socket being pressed against corresponding contacts as a result of the package of an IC being pressed against the socket. Unfortunately, the pressure required to press each pin of a socket against each corresponding pin of a package requires a certain quantity of force to ensure a good electrical connection, and this pressure is cumulative, such that the amount of force required goes up with the number of pairs of corresponding contacts that must be pressed together. This cumulative amount of force can pose various mechanical design challenges, including the need to evenly spread the force across all of the corresponding pairs of pins to ensure that each receives the required amount of force without receiving an excessive quantity of force. Where very large numbers of corresponding pairs of pins are involved, causing a great deal of cumulative force to be required, concerns arise about ensuring the even application of force so as to not physically damage either the socket or the package of the IC.